Heft and build inspire confidence; great shooting experience. F4 more than acceptable. Very sharp; nice bokeh. Very usable focal length, of course.

Cons:

82mm filters expensive; forced to buy new ones.

Has quickly become one of my favorite lenses--ever. IQ is inspiring. Very good sharpness; nice depth for a zoom. Focus and zoom are both smooth as butter. Image stabilization works well. No focusing problems. Sigma has really stepped up their QC. A lens that is pure joy to use.

I checked the Nikon version on the Nikon d7000. Overall a very good lens, but not so good that the latest 18-35 or 35 f/4. Very usable at f/4 at both ends, but not tack sharp. CA is low, on Full frame vignetting is high. What is exceptional is the build quality, this lens feels and looks like a very high quality product, even compare to the most expensive lenses.

Weight, some vignetting on FF, but this is no different than Canons own

Good solid build, smooth zoom and fast and accurate AF, always manual overridable if desired. Some vignetting on full frame sensor, but this is normal, not an issue on APS-C. Sharp images, good color, hard to provoke flares. Decent DOF with nice soft blur. Next to none CA. On par with Canons own equivalent. Sunshade and bag included